150 SYNOPSIS OF BRITISH SEAWEEDS. 



ceedingly slender, flaoeid, and byssoid, much divided; the 

 branches lanceolate in outline, virgate, Bel with nun* 

 long, slender, flexuons, pinnate or subbipinnate plumules; 

 articulations of the branches eight times, of the ramuli four 



times as long as broad ; tetraspores, one or two, Bessile on 



the pinnules, elliptical; faveUse binate, Bubterminal, Am. 



MSS. Hart, in Jlook. Br. FL v. 2.j». 342. (Atlas, PL 



LVIII. Fig. 269.) 

 Hab. On several Alga?, in tide-pools near low- water mark ; on 



Codinm tomentosum especially. Annual. Summer. 

 E. bys8oideum is one of the softest and most gelatinous 

 of the genus, having exceedingly slender fronds, growing 

 in dense tufts. To the naked eye it frequentl} T bears much 

 resemblance to C. eorymbosum, so much that it sometimes 

 requires a microscope to determine to which species the 

 specimen under examination may belong. The ultimate 

 branching and the position of the tetraspores will then 

 afford an easily seen character, by which the two plants 

 may be distinguished. From C. roseum our plant is chiefly 

 known by its much greater delicacy and softer substance, 

 and its adhering much more closely to paper, and being 

 more glossy when dry. 



263. polyspermum {The many-seeded Callithamnidn) ; tufts 

 globose ; filaments slender, delicate, loosely much-branched, 

 irregularly divided below, distichously plumulate above ; 

 plumules long and narrow, simply pinnate ; pinnae short, 

 simple, patent, acute, spine-like ; articulations of the branches 

 with a very narrow coloured tube, four or five times as long 

 as broad, of the ramuli short ; tetraspores globose, lining 

 the inner face of the pinna?, Ag. Sp. Alg. v. 2. p. 169. 

 (Atlas, PI. LVIII. Fig. 270.) 

 Calhthamnion Grevillii, Harv. C. roseum, Grrev. C. purpuras- 



cens, Johnst. Phlcbothamnium polyspermum, Ktz. 

 Hab. On various Alga?, between tide-marks ; frequently on Fucus 

 vesiculosus and F. serratas. Annual. Summer. 

 A common species, variable in its characters, gradually 

 approaching C. roseum on the one hand, and C. ffookcri 

 on the other. The typical form of the species is remark- 

 able for the short, awl-shaped, simple pinna?, beaded on 

 the inner face with globose tetraspores. It more fre- 

 quently grows on the coarser Fuci than any other species, 

 and sometimes clothes them with densely set, globose tufts, 

 which in old-age become blended together, concealing the 

 greater part of the plant on which they grow. 



